1. Field of the Invention
The present invention relates to a tubular body, a bass reflex port, and an acoustic apparatus such as a bass reflex speaker.
2. Description of Related art
There is known an acoustic apparatus, such as a bass reflex speaker, configured to enhance the bass positively utilizing sound from the rear of a speaker unit, as disclosed in the following Patent Literature 1. The acoustic apparatus such as the bass reflex speaker includes, in its enclosure (cabinet), a speaker unit and a bass reflex port. The bass reflex port is constituted by a tubular body which is open at its opposite ends and which is fixed at one open end thereof to an opening portion formed in the enclosure of a speaker of the speaker unit. In the acoustic apparatus, air outside the enclosure is suck or taken in into the enclosure via the bass reflex port, and air inside the enclosure is discharged out of the enclosure via the bass reflex port.
FIGS. 7A and 7B are cross-sectional views each showing a structure of a portion of an acoustic apparatus in which a conventional bass reflex port is disposed. As shown in FIG. 7A, a conventional bass reflex port 20A has a cross-sectional shape that is constant dimension from one end to the other end thereof. In the bass reflex port 20A, its inner wall is orthogonal to a baffle panel. The acoustic apparatus having the thus formed bass reflex port 20A suffers from extraneous or abnormal noise (the so-called wind noise) generated from the bass reflex port 20A, which noise arises from suction and discharge of air in the bass reflex port 20A. In view of this, in a conventional bass reflex port 20B shown in FIG. 7B, each of end portions respectively near to opposite ends of the bass reflex port 20B has a flare shape in which an air flow passage via the bass reflex port 20B, namely, a space enclosed with an inner wall of the bass reflex port 20B, gradually widens radially from the middle toward the opposite ends of the bass reflex port 20B, whereby extraneous noise generated from the bass reflex port 20B is reduced.
Patent Literature 1: JP-A-2012-161109